PROJECT SUMMARY/ABSTRACT Cannabis is the most widely used illicit drug and rates of hazardous use, and cannabis use disorders (CUDs), have continued to rise in recent years. Increased exposure produces higher risk for detrimental psychological and behavioral effects of cannabis use. Given this increased prevalence of problematic cannabis use, identifying effective behavioral strategies for individuals experiencing problems with addiction would offer significant benefits. Exercise, particularly resistance exercise, is a behavioral intervention with considerable potential as an adjunctive treatment for CUD. No prior study has investigated the effects of an acute bout of resistance exercise on cannabis craving and consumption, nor has prior research identified what psychobiological mechanisms may underlie these exercise potentiated effects. The aims of this proposal seek to address these issues by implementing an acute resistance exercise protocol in men and women who have severe cannabis use disorder. This proposal will examine the acute effects of resistance exercise on craving, mood, anxiety, withdrawal symptoms and markers of reward and stress regulation. In addition, this proposal will examine the trajectory of these effects in the subsequent days. Given the NIH/NIDA goal to develop new and improved treatment to help people with substance used disorders achieve and maintain a meaningful and sustained recovery, resistance exercise is a treatment that could produce promising results. Resistance exercise is an intervention that is both easy to implement, readily available, could support abstinence and address psychological effects associated with early withdrawal. The findings of this study will inform the further development of exercise interventions for individuals with cannabis use disorder.